1. Field of the Invention
The invention relates to an apparatus for tilting a carrier for optical elements with two optical faces which are arranged together on a carrier and are fixed at a fixed angle to one another, the carrier being fastened on a base plate via articulated connections.
More specifically the invention refers to two mirrors, e.g. plane mirrors as optical elements and also for a beam splitter as optical element.
2. Description of the Related Art
In the case of optical systems with a plurality of optical axes, the light beams are deflected by mirrors, prisms or beam splitters. For this purpose, it is known, for example, for two plane mirrors, which form a fixed angle between them, to be arranged on a common carrier. The optical elements adjacent to the carrier have to be aligned precisely in relation to one another, this also requiring, for example, precise air clearances to be maintained. If the air clearances are co-ordinated, and the three dihedral angles of the mirror carrier are pre-adjusted, problems arise for the precision adjustment of the dihedral angle. If the tilting angle of one of the two mirrors changes, then this change likewise results in a change in tilting and air clearance for the other mirror, since the two mirrors are fixed to one another. For this reason, in some circumstances, a number of high-outlay follow-up adjustments are then necessary. The mirror carrier thus has to be adjusted in at least five degrees of freedom. If the precise location of the mirror carrier is adjusted beforehand, the latter just has to be tilted about three spatially arranged axes for an orientation adjustment.
In the case of known tilting apparatuses, then, a change in tilting angle in the case of one of the two mirrors is also associated with a change in location of the mirror carrier. The location of the mirror carrier is designed, for example, via a reference point RP which is spaced apart from an adjacent optical element by a certain distance a and from another optical element by a certain distance b. In the case of known changes in tilting angle for a mirror, the reference point is displaced, as a result of which the values a and b also change, as does the location of the mirror carrier. It is thus disadvantageously necessary for the location of the mirror carrier and the values a or be to b corrected again.
This means that there are two problems. If the air clearances are left unchanged or are included in the calculation, then the location of the apparatus has to be adjusted precisely beforehand. The advantage of this configuration is that there is no need for any reference point for adjustment purposes.
In the case of a second, more straightforward type of adjustment, in contrast, a reference point is required. In this case, however, the air clearances are not yet provided and adjustment via an image or via optical imaging is not possible, in some circumstances, due to the lack of imaging. In order to co-ordinate the air clearances, the mirror carrier then also has to be rotated correspondingly about the defined reference point RP. In the case of the first-mentioned possibility, in which case the air clearances are included in the calculation, an optical image may already be present for the precision adjustment of the tilting.